The unfortunate soldier was seen being stretchered from a rehearsal for Trooping the Colour this morning.

This is not the first time members of the military have fainted during the historic event.

A soldier fainted in front of Kate Middleton during last year's ceremony and in 2012 another fell victim to the 23C heat.

Temperatures reached 26.3C at London's Heathrow today in what was the hottest day of the year so far.

TROOPING THE COLOUR: The soldier is not the first to fall victim to the weather [WENN]

Much of the UK enjoyed balmy temperatures well above the May average.

Met Office spokesman Dan Williams said: "Gravesend in Kent saw a maximum of 26C (78.8F) and there were a few other places close to that around the South East. "A good chunk of England has seen temperatures of 20C (68F) and above today.

"It's only in far western places areas like Cornwall that it hasn't got above 20C but even these places were in the high teens.

"The lowest UK maximum has been around 12-13C (53.6-55.4F) in Northern Ireland and parts of Scotland."

Although much of the country basked in warm temperatures, parts of Wales saw heavy downpours and some intense spells of thunder and lightning.

The mercury is not expected to reach as high tomorrow, although East Anglia and the East Midlands should get maximums of around 22C (71.6F).

Saturday was also exceptionally busy, with a total of 6,137 emergency calls recorded, compared to just over 5,000 calls the previous weekend.

At Saturday's busiest, staff taking and handling calls in the control room took 403 calls an hour, between 11pm and midnight.

Kevin Brown, LAS deputy director of operations, said: "We always see a rise in calls to our service in hot weather – but this weekend in particular there were a variety of reasons including the big turnout for the FA Cup final in Wembley.

"It is important people help us to respond to the most seriously ill and injured by only calling 999 in a genuine emergency.

"Anyone with a minor condition should consider other health care options such as visiting their GP, local pharmacy or calling 111.

"Many people call us with heat-related issues that could be avoided if they took more care in the sun, and we would again urge people to look after themselves."

The service said it was urging people to check on friends, relatives and neighbours who could be vulnerable during the hot weather. People are urged to wear hats when outside, use plenty of sun cream, drink plenty of water and avoid alcohol consumption in the sun.

Medicines for conditions such as asthma and bronchitis should be carried, the service warned.